In addition to analysing data on drug use in our original panel of schools, funds are requested to analyse data collected in year 04 under a supplementary grant, and to carry out the new activities described below. (1) Analysis of methodological experiment: Data were collected in an experiment comparing reported drug use obtained from matched samples of 11th grade students in two different settings -- at school and at home. In addition to comparing reported drug usage in these two settings, other analyses will compare reported usage by young people whose parents were home at the time of the study, with those whose parents were not home, as well as exploring other relationships and correlates of drug use. (2) Analysis of data from additional junior high schools: In 1973, 7,000 additional junior high school students were included in our study, providing sufficient cases to permit comparisons of drug use patterns in different types of schools on both coasts. Inter-school and intra-school analyses will be made of behavioral and other correlates of drug use by various types and amounts of drugs used. (3) Addition of school with large Puerto Rican population. A team of investigators from the University of Puerto Rico School of Public Health has been funded to study drug behavior among high school youth on the island, and we would like to undertake a comparative study among youth in one U.S. school with a largely Puerto Rican population to increase understanding of cross-cultural factors in adolescent drug behavior. (4) Replication of study of England. A sub- contract has been made with the Institute for the Study of Drug Dependence to assist in modifying our questionnaire to be suitable for English students and several English schools have agreed to conduct comparable studies among their students. Funds are requested for data collection and data processing of this study.